This shipment of goods has the effect of converting French currency into English. For this to work the merchants involved would need to have the volume of trade necessary to accommodate the substantial sums that were to be moved. Wine to England would have been one of the obvious products involved, but it is also possible that wine and other products were sent to the new colonies, with products from those colonies being sent back to England.
The other critical element would have to be trust. The English merchants were receiving goods from France for which they did not have to pay. Hence they will have known what the implications were, and if they were in any doubt, the fact that they were delivering money directly to the French Ambassador and William Chiffinch would have removed this.
I do not know what customs documents would have been required at that time, but I suspect that a bill of sale with a statement of value was all that was required; customs then being paid in the normal manner. I note here that John Thompson had married Arthur Annesley’s daughter in 1668. Thompson was High Sheriff of Buckinghamshire 11.11.1669 to 4.11.1670. On 13.5.1670, a month before the signing of the Treaty of Dover, he was granted a licence to ‘live beyond the seas’ (France) for six months, which was an unusual permission for a serving Sheriff. On his return he was in 1671 appointed a Customs Commissioner, and retained this office until removed by Danby in 1675. His father was Maurice Thompson, probably the most successful merchant of his time. Thompson’s uncle was Sir William Thompson, a Commissioner for Trade 1660-72, and Governor of the East India Company 1664-6 and again in 1676-8. Robert Thompson was Deputy-Governor 1670-2.
I note too that in the second half of October 1670 the Marquis de Seignelay sent a letter to his father: ‘C’est une chose fort agreeable a voir que le port de Bordeaux pendant la foire. La ville paroist dans l’enfoncement, et le port , qui est en croissant et qui s’appelle a cause de cela le ‘Port de la Lune’, est orne de 7-800 vaisseaux, tant Francois et d’estrangers, qui viennent charger les vins, qui sont toute la fortune du pays’.